categoryZGrasses Grasses List 

FLAT-SEDGE

FLAT SEDGE

Blysmus compressus

Sedge Club- & Spike-Rush Family [Cyperaceae]

month8jun month8june month8jul month8july

category
category8Grasses
 
status
statusZnative
 
flower
flower8brown
(bisexual)
inner
inner8cream
 
petals
petalsZ0
 
type
typeZspiked
 
stem
stem8flat
 
rarity
rarityZuncommon
 
sex
sexZbisexual
 

21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
It grows to 45cm long - the roots are just before the toes of the boot, the plant here with some yellowish-green leaves whilst others are a brighter green than surrounding plants..


21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
This is near the top of it; note that it only has one floret, and that is flat with a short, tight inflorescence with now-browned branches on alternate sides of the main stem. And a few long narrow leaves each side.


21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
The now-brown florets alternately opposite.


2012, Teesdale Photo: © Dawn Nelson
It is NOT a true sedge (it is one of the two Flat-sedges), and that is why there is only one flower spike - which is bisexual (and not 3 or 4 independant spikes of male and female flowers as it is for the true sedges).

For a start, the STEMS are not triangular in cross-section as they are for True Sedges, but rather they are thin and grass-like - looking much more like grass leaves rather than stems (hence the 'flat' moniker of 'Flat Sedge') . These flat stems also feel rough to the touch.

The flowers are in one! short spike with long pale-coloured anthers and styles.



2012, Teesdale Photo: © Dawn Nelson
The spikelets are in two rows of opposite pairsand are between 4 and 10mm long and number from 10 to 20 and are reddish-brown.

The very lowest spikelet is the odd one out looking more like a leafy bract or similar to a glume. This specimen has a long thin green object protruding far out.



2012, Teesdale Photo: © Dawn Nelson
Being bisexual the numerous curly white objects protruding from the tip of each spikelet must be the styles (and anthers?), but your Author cannot tell which is which. The nut fruit is between 1.5 to 2mm long, but your Author cannot see any.


21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
The stem with a few leafy branches.


21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
The stems and leaves have vertical rows of very short whitish pimples which make it feel slightly rough to the touch.


21st July 2018, Green Beach, Ainsdale, Sefton Coast Photo: © RWD
The very short hairs in vertical lines are probably made of silicon dioxide, SiO2, which is what sand contains (amongst a few other minerals).


It is native and grows in damp grassland and salt-marshes inland of the sea, or no bare ground beside the sea. Also on dune-slacks amongst grass. It is only locally frequent on the coasts of Britain and Ireland but common in West Scotland. Beware of the similar Saltmarsh Flat-Sedge (Blysmus rufus) which also grows in saltmarshes near the sea. This too has spikelets on opposite sides, but there are usually fewer of them, only 3 to 8 (rather than the 10 to 20 of Flat-sedge)


  Blysmus compressus  ⇐ Global Aspect ⇒ Cyperaceae  

Distribution
 family8Sedge Club- & Spike-Rush family8Cyperaceae
 BSBI maps
genus8Blysmus
Blysmus
(Flat-Sedges)

FLAT-SEDGE

FLAT SEDGE

Blysmus compressus

Sedge Club- & Spike-Rush Family [Cyperaceae]